r4695 merged to trunk; trunk now becomes 0.5.

0.4 development continues at /sqlalchemy/branches/rel_0_4

1 files changed, 107 insertions, 0 deletions

diff --git a/lib/sqlalchemy/log.py b/lib/sqlalchemy/log.py
new file mode 100644
index 000000000..65100d469
--- /dev/null
+++ b/lib/sqlalchemy/log.py
@@ -0,0 +1,107 @@
+# log.py - adapt python logging module to SQLAlchemy
+# Copyright (C) 2006, 2007, 2008 Michael Bayer mike_mp@zzzcomputing.com
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: http://www.opensource.org/licenses/mit-license.php
+
+"""Logging control and utilities.
+
+Provides a few functions used by instances to turn on/off their logging,
+including support for the usual "echo" parameter.
+
+Control of logging for SA can be performed from the regular python logging
+module.  The regular dotted module namespace is used, starting at
+'sqlalchemy'.  For class-level logging, the class name is appended, and for
+instance-level logging, the hex id of the instance is appended.
+
+The "echo" keyword parameter which is available on some SA objects corresponds
+to an instance-level logger for that instance.
+
+E.g.::
+
+    engine.echo = True
+
+is equivalent to::
+
+    import logging
+    logger = logging.getLogger('sqlalchemy.engine.Engine.%s' % hex(id(engine)))
+    logger.setLevel(logging.DEBUG)
+"""
+
+import logging
+import sys
+
+
+rootlogger = logging.getLogger('sqlalchemy')
+if rootlogger.level == logging.NOTSET:
+    rootlogger.setLevel(logging.WARN)
+
+default_enabled = False
+def default_logging(name):
+    global default_enabled
+    if logging.getLogger(name).getEffectiveLevel() < logging.WARN:
+        default_enabled = True
+    if not default_enabled:
+        default_enabled = True
+        handler = logging.StreamHandler(sys.stdout)
+        handler.setFormatter(logging.Formatter(
+            '%(asctime)s %(levelname)s %(name)s %(message)s'))
+        rootlogger.addHandler(handler)
+
+def _get_instance_name(instance):
+    # since getLogger() does not have any way of removing logger objects from
+    # memory, instance logging displays the instance id as a modulus of 16 to
+    # prevent endless memory growth also speeds performance as logger
+    # initialization is apparently slow
+    return "%s.%s.0x..%s" % (instance.__class__.__module__,
+                             instance.__class__.__name__,
+                             hex(id(instance))[-2:])
+    return (instance.__class__.__module__ + "." + instance.__class__.__name__ +
+            ".0x.." + hex(id(instance))[-2:])
+
+def class_logger(cls):
+    return logging.getLogger(cls.__module__ + "." + cls.__name__)
+
+def is_debug_enabled(logger):
+    return logger.isEnabledFor(logging.DEBUG)
+
+def is_info_enabled(logger):
+    return logger.isEnabledFor(logging.INFO)
+
+def instance_logger(instance, echoflag=None):
+    if echoflag is not None:
+        l = logging.getLogger(_get_instance_name(instance))
+        if echoflag == 'debug':
+            default_logging(_get_instance_name(instance))
+            l.setLevel(logging.DEBUG)
+        elif echoflag is True:
+            default_logging(_get_instance_name(instance))
+            l.setLevel(logging.INFO)
+        elif echoflag is False:
+            l.setLevel(logging.NOTSET)
+    else:
+        l = logging.getLogger(_get_instance_name(instance))
+    instance._should_log_debug = l.isEnabledFor(logging.DEBUG)
+    instance._should_log_info = l.isEnabledFor(logging.INFO)
+    return l
+
+class echo_property(object):
+    __doc__ = """\
+    When ``True``, enable log output for this element.
+
+
+    This has the effect of setting the Python logging level for the namespace
+    of this element's class and object reference.  A value of boolean ``True``
+    indicates that the loglevel ``logging.INFO`` will be set for the logger,
+    whereas the string value ``debug`` will set the loglevel to
+    ``logging.DEBUG``.
+    """
+
+    def __get__(self, instance, owner):
+        if instance is None:
+            return self
+        else:
+            return instance._should_log_debug and 'debug' or (instance._should_log_info and True or False)
+
+    def __set__(self, instance, value):
+        instance_logger(instance, echoflag=value)